Variable-speed drive



June 28, 1949. L. PERI-mcs v2,474,789

VARIABLE SPEED DRIVE Filed June 1, 1945 INVENTOR. L. es. f z' E j: s1-'fz c1. D.:

Patented June 28, 1949 `UNITED STATES PATENT OFFICE 1 Claim.

1 This invention has to do with variable speed drive devices, having as an object the provision `of a simple, eicient and highly economical device of this character.

More specifically, it is an object of my invention to provide a device by which the driving speed may be easily and quickly changed by means of movement of a core or mandrel in the hollow drive shaft, upon which shaft pulleys are rotatively mounted.

Another object is the provision of a variable speed device which performs its speed changing functions without utilizing any gears or elements subject to being stripped by stresses resulting from abrupt speed changes.

An additional object is the provision of a device of this character wherein the stresses upon the cooperating parts due to speed changes are reduced to a minimum.

I shall describe one preferred embodiment, from which explanation various other objects and advantages will become apparent, although I wish it understood that the invention, in its broader aspects, is not intended to be restricted to the particular embodiment and details shown in the accompanying drawings and now to be described.

In the accompanying drawings forming a part of this invention:

Fig. l is a medial longitudinal section; Fig. 2 is a sectional view forming a continuation `of Fig. 1;

Fig. 3 is a section on line 3--3`of Fig. 1; and

Fig. 4 is a reduced top plan view of a device embodying my invention.

Referring now to the embodiment of the invention shown in the drawings, the numeral 5 denotes a driven shaft journalled in bearings 1, -8, and having annular ilange 9, an axial bore I0 having a reduced diameter portion Illa, and having radial openings Il, I2 within which the respective balls I5, I6 loosely fit. The shaft 5 is adapted to be connected to a motor, not shown.

Between the reduced diameter right-hand end portion of the shaft and bearing 8 are mounted bearing races I8, carrying ball bearings I9. The inner race is secured by a nut Illa.

Pulleys 20, 22, having V-shaped belt grooves, are rotatably mounted on the shaft 5, being provided With needle bearings 24, 26, pulley 2B having a relatively hardened bushing 21 presenting in its bore a concaved or spherical recess 30 conforming to the surface of the ball I5. Pulley 22 is not shown as being provided with a similar bushing, since it is not subject to as great stresses as the larger pulley, but there is provided in the CTI bore of pulley 22 a concaved recess 3'2 conforming to the surface of ball I6. Of course, if desired, a hardened bushing similar to that of bushing 21 may be utilized in pulley 22.

It will be apparent from the foregoing description that either of the pulleys 2D, 22 may be locked to the shaft 5 by means of the ball I5 or I6 being cammed or forced outwardly in the opening Il or I2 and into the recess 30 or 32. To accomplish this, I provide a mandrel or core which is axially slidable in the bore of the shaft 5 and has an annular groove 31 curved at its opposite ends to provide cam surfaces 31a, 311i.

A plunger having a ball-shaped end portion is rotatably connected into the recessed shank end of the mandrel by means of a threaded plug 42 through which the stem of plunger 40 slidably extends, the latter being operatively connected to a manually operable push and pull knob 45 by means of a iiexible wire or cable 41 slidably disposed in a sheathing 43, the latter carrying a ferrule 49 secured to the reduced diameter threaded outer end of the bearing 8 by collar 50.

It will be observed that by sliding' the mandrel 35 to the right (into the position shown inthe drawings) ball I5 is permitted to move out of the recess 30 in the pulley 20 and thus free that pulley to rotate relative to shaft 5, while the cam surface 31h will move ball I6 into engagement in the recess 32 and consequently fix pulley 22 to the shaft. Pulley 22 is operatively connected by a V-belt to a larger diameter pulley 56 while pulley 2|) is operatively connected by belt 51 to a smaller diameter pulley 58.

To restrain the balls I5, I6 from undue movement radial to the mandrel when either of the balls is freed from locking engagement between the shaft and pulley, I provide for each ball a spring-loaded detent or plunger slidably mounted in a longitudinal bore in shaft 5 parallel to bore IIJ, and being urged against the ball by a spring 6I seating at its other end against a threaded plug 62. Each of these plungers has a pointed end disposed to engage the ball at a point offset from its center so that it tends to yieldably retain the ball in either of its positions.

To lock pulley 20 to the shaft the mandrel is pushed to the left, permitting ball I6 to move out of engagement with pulley 22 and forcing ball I5 into engagement with pulley 2U. 'I'he cam surfaces are so spaced in relation to the spacing of the balls axially of the drive shaft that in the course of effecting a speed change there is a momentary period during which neither of the pulleys is positively locked to the shaft, so that the amava@ ball being moved out oniocking engagement with the pulley will tend to 'be forced inwardly olf the opening il by virtue of the inertia of the free pulley and the spherical shape of the ball and recess. After the ball ls moved inwardly of the opening, the plunger 60 will ,vleldably oppose radial movement of the ball.

This shifting or changing of speeds may be accomplished during rotation of the shaft 5 Without undue stresses because the mandrel and balls move vwith the shaft and the appropriate ball member merely has to engage in the appropriate curved recess, which engagement is positively accomplished by the cam surfaces.

I claim:

A clutch for selectively locking one o! a pair of recessed pulleys on a hollow shaft presentinglongitudinally spaced radial openings underlying the respective pulleys, comprising a ball oatlngly mounted in each opening, and means i'or selectively moving said balls into engagement with said respective recesses whereby selectively to lock the pulleys on the shaft, comprising a mandrel axially slidably mounted in the shaft bore,

'4 said mandrel having an annular groove whose opposite side walls provide oppositely disposed curved cam surfaces engageable with the respective balls in response to axial movement of the mandrel in said bore, and a pair of spring-loaded detent means normally engaging the respective balls in directions axially of the shaft. each oi said members being slldably mounted in an auxiliary bore in the shaft parallel with the rstmentioned bore. l

` LESLIE PERHACS.

REFERENCES CITED 'I'he followingreferenlces are of record ln the file of this patent:

UNITED STATES PATENTS Number Name Date 439,316 White Oct. 28, 1890 1,015,254 Whisler Jan. 16, 1912 1,895,821 Rueckart et al. Jan. 31, 1933 1,909,522 Collins May 16, 1933 2,034,767 Neracher Mar. 24, 1936 2,377,575 Ringer June 5. 1945 

